Apparatus and method for facilitating the connection of pipes

ABSTRACT

An apparatus for facilitating the connection of pipes comprises a rotary ( 4 ) and a stator ( 5 ), the rotary comprising at least one hydraulically actuated jaw ( 24,25,26 ), and a pump ( 58 ) arranged on the rotary ( 4 ) for pumping hydraulic fluid for actuation of the or each jaw ( 24,25,26 ), the stator comprising a motor ( 55 ) arranged on the stator ( 5 ), so that rotational energy can be transferred from the motor to the pump in an operational configuration.

This invention relates to an apparatus and a method for facilitating theconnection of pipes, and more particularly, but not exclusively, to apowered drill pipe tong for facilitating the connection of sections orstands of drill pipe.

Drill pipe tongs are commonly used for facilitating the connection ofsections or stands of drill pipe to a pipe string. Typically, the pipestring hangs in a wellbore from a spider in a floor of an oil or gasrig.

A section or stand of drill pipe to be connected to the pipe string isswung in from a drill pipe rack to the well centre above the pipestring. A pipe handling arm may be used to guide the drill pipe to aposition above the pipe string. A stabbing guide may then be used toalign a threaded pin of the drill pipe with a threaded box of the pipestring. A drill pipe tong is then used to tighten the connection to atorque of typically 68,000 Nm (50,000 lb.ft).

The drill pipe tong is also used for disconnecting drill pipe. Thisoperation involves breaking the connection which requires a torquetypically greater than the tightening torque which may typically be usedin the order of 11,000 Nm (80,000 lb.ft).

A drill pipe tong generally comprises jaws mounted in a rotary which isrotatably arranged in a housing. The jaws are moveable relative to therotary in a generally radial direction towards and away from an upsetpart of the pipe to be gripped. The upset parts of the pipe aregenerally located above the pin and below the box of the pipe and havean enlarged outer diameter and/or a reduced inner diameter.

In use, the rotary is rotated forcing the jaws along cam surfacestowards the upset part of the section of pipe. Once the jaws fullyengage the upset part, the rotary carries on rotating applying torque tothe threads and hence tightens the connection between the section ofpipe and the pipe string.

Several problems have been observed with such prior art drill pipetongs.

In particular, such drill pipe tongs can badly scar the upset part ofthe pipe, particularly if the jaws start rotating relative to the drillpipe.

Once scarred, the pipe is then lowered into the wellbore. Frictionbetween the wellbore (or casing lining the wellbore) and the scarredupset grinds the upset, reducing the diameter.

Scarring of the upset may also be caused by having to reapply the jaws.This is especially common when connecting pipe with “wedge threads”which requires approximately 80° of turn in order to torque theconnection. Many prior art wrenching tongs need to be reapplied to thepipe every 25°.

A reduction in diameter of the upset requires the use of a drill pipetong or for the old drill pipe tong to be modified therefor.

An attempt at solving this problem is disclosed in PCT publicationNumber WO 92/18744, which discloses a rotary comprising hydraulicallyoperated active jaws and stationary passive jaws. The hydraulicallyactivated jaws are engaged fully with the pipe prior to rotation of therotary, thereby substantially reducing scarring. A hydraulic circuit isprovided on the rotary for actuating the jaws. A plunger is used toactivate the hydraulic system by depressing a hydraulic piston of thehydraulic circuit repeatedly. This operation takes time. If severalseconds can be saved per connection, the overall cost of theconstruction of an oil or gas well can be drastically reduced, as longas reliability is not sacrificed.

Another problem associated with the rotary disclosed in PCT PublicationNumber WO 92/18744 is that repeated depressing of the plunger forengaging the jaws fully with the pipe may itself cause some scarring.

A further problem associated with power tongs is how to move jaws intoengagement with a tubular with sufficient force and sufficient speed.

A still further problem associated with a rotary for power tong is howto fit a mechanism for applying jaws to a tubular into the confinedspace of a rotary. In particular, the problem arises that if a pump isprovided on the rotary for pumping hydraulic fluid, the means ofsupplying power to the pump must be disconnected before the rotary canbe rotated to torque the connection between pipes. This further adds tothe overall time of the operation.

If a pump is not provided on the rotary, the hydraulic pressure must beprovided via a hose attached to the rotary, and this also must bedisconnected before the rotary can be rotated.

Accordingly, a first aspect of the invention provides an apparatus forfacilitating the connection of pipes, which apparatus comprises a rotary(4) and a stator (5), said rotary (4) comprising at least one jaw(24,25,26), at least one piston (15,16,17) arranged in at least onecylinder (18,19,20) for actuating said at least one jaw (24,25,26), anda hydraulic circuit (100) linking a first chamber in front of saidpiston (15,16,17) and a second chamber to a rear side of said piston(15,16,17) such that, in use, hydraulic fluid is expelled from one ofsaid first or second chambers and replenishes the other of said firstand second chambers.

Other features of the first aspect of the invention are set out inclaims 2 to 12.

There is also provided a method for facilitating the connection ofpipes, comprising engaging a motor attached to a stator with a pumpattached to a rotor and transferring rotational energy from the motor tothe pump, enabling the pump to drive hydraulic fluid to actuate at leastone jaw. In a preferred embodiment, the method comprises the step ofmoving the motor from a first position in which it is disengaged fromthe pump to a second position in which the motor and the pump areengaged to transfer rotational energy from the motor to the pump. Asecond aspect of the invention provides an apparatus for facilitatingthe connection of pipes which apparatus comprises a rotary and a stator,said rotary comprising at least one jaw, at least one piston arranged inat least one cylinder for actuating said at least one jaw, and ahydraulic circuit linking a first chamber in front of said piston and asecond chamber to a rear side of said piston such that, in use,hydraulic fluid is expelled from one of said first or second chambersand replenishes the other of said first or second chambers.

There is also provided a method for facilitating the connection ofpipes, the method using the apparatus of the first aspect of theinvention, the method comprising the step of expelling hydraulic fluidfrom one of said front or rear sides of said piston and replenishing theother of said front or rear sides of said piston.

A third aspect of the invention provides an apparatus for facilitatingthe connection of pipes which apparatus comprises a rotary and a stator,said rotary comprises at least one jaw and at least one piston arrangedin at least one cylinder for actuating said at least one jaw, and ahydraulic circuit, wherein said hydraulic circuit comprises a valvepreventing return flow of hydraulic fluid and a restriction such that,in use, the arrangement allows a finite force to be applied to saidpipe.

There is also provided a method for facilitating the connection ofpipes, the method using the apparatus of the second aspect of theinvention, the method comprising the step of allowing hydraulic fluid toleak from said hydraulic circuit such that said at least one jaw appliesa finite force to said pipe.

For a better understanding of the invention, reference will now be made,by way of example, to the accompanying drawings, in which:

FIG. 1 is a perspective view of an apparatus in accordance with theinvention prior to use;

FIG. 2 is a top plan view, partly in cross-section of part of theapparatus of FIG. 1;

FIG. 3A is a top plan view of the apparatus of FIG. 1 in a first stageof operation;

FIG. 3B is a perspective view of part of; the apparatus of FIG. 1 in afirst stage of operation.

FIG. 4A is a top plan view of the apparatus of FIG. 1 in a second stageof operation;

FIG. 4B is a perspective view of part of the apparatus of FIG. 1 in asecond stage of operation.

FIG. 5 is a perspective view of a part of the apparatus of FIG. 1;

FIG. 6 is a perspective view of another part of the apparatus of FIG. 1;

FIG. 7 is a schematic diagram of a part hydraulic, part mechanicalcircuit used in the apparatus of FIG. 1 in a first stage of operation;

FIG. 8 is a schematic diagram of the part hydraulic, part mechanicalcircuit of FIG. 7 in a second stage of operation;

FIG. 9 is a schematic diagram of the part hydraulic, part mechanicalcircuit of FIG. 7 in a third stage operation;

FIG. 10 is a schematic diagram of the part hydraulic, part mechanicalcircuit of FIG. 7 in a fourth stage of operation;

FIG. 11 is a cross sectional view of an arrangement of part of theapparatus of FIG. 1; and

FIG. 12 is a cross sectional view of an alternative arrangement shown inFIG. 12.

Referring to FIG. 1 there is shown an apparatus which is generallyidentified by reference numeral 1.

The apparatus 1 comprises a drill pipe tong 2 and a backup unit 3.

The drill pipe tong 2 comprises a rotary 4 and a stator 5.

Referring to FIG. 2, the rotary 4 comprises a housing 6 which isprovided with a toothed ring 7 for engagement with toothed drive wheelsin a stator 5 of the drill pipe tong 2. The housing 6 is also providedwith an opening 8 for receiving a drill pipe.

Three piston and cylinders 9, 10 and 11 are arranged about the rotary 4spaced at 120° to each other and are directed to the centre of therotary 4. The piston and cylinders 9, 10 and 11 comprise static pistons12, 13 and 14 each provided with a piston head 15, 16 and 17. Cylinders18, 19 and 20 are slideable along said piston heads 15, 16 and 17towards and away from the centre of the rotary 4. Sealing rings 21, 22and 23 are provided in the piston heads 15, 16 and 17 between the pistonheads 15, 16 and 17 and the cylinders 18, 19 and 20.

Cylinders 18, 19 and 20 are provided with jaws 24, 25 and 26 forengaging with the upset of a drill pipe. The jaws 24 and 25 are locatedin corresponding dovetail slots 27 and 28. The cylinder 20 is shownprovided with an extension member 29 between the cylinder 20 and thejaws 26. The extension member 29 is located in dovetail slots 30 and thegripping elements 26 are located in corresponding dovetail slots 31 inthe extension member 29. In use, either all of the cylinders 18, 19 and20 are provided with extension members 29 or none of the cylinders 18,19 and 20 are provided with extension members 29.

Hydraulic lines 32, 33 and 34 and hydraulic lines 35, 36 and 37 arearranged in each piston 12, 13 and 14 for the provision of hydraulicfluid in front of and behind the piston heads 15, 16 and 17.

Two release valves 38 and 39 are arranged on the housing 2. The releasevalves 38 and 39 are used for retracting cylinders 9, 10 and 11 andhence disengaging the gripping elements 24, 25 and 26 from a section ofstand of drill pipe.

Referring to FIG. 11, the rotor 4 has a cover plate 40 through which therelease valves 38 and 39 can be accessed. The release valves 38 and 39may be operated manually or operated by activating mechanisms, twosuitable activating mechanisms are shown in FIGS. 11 and 12.

The release valves 38 and 39 are arranged on opposite sides of therotary so that, when release of the gripping elements 24, 25 and 26 fromthe drill pipe is required, at least one will be under an activatingring 41, the activating ring 41 being broken across the opening 8. Sixactivating valves 42 are arranged about the activating ring 41 in lid 43of the stator 5. Each activating valve 42 comprises a piston housing 44,a cylinder 45, a piston 46, a return spring 47 and a port 48. When it isdesired to activate the release valves 38 and/or 39, pneumatic orhydraulic fluid pressure is applied via a control panel (not shown)through port 48 into cylinder 45, displacing piston 46. The piston 46pushes ring 41 on to plate 49 above release valve 39, and/or plate (notshown) above release valve 38. The plate 49 is retained at one end on abolt shaft 50 to cover plate 40, and at the other end to a plunger 51which is slideably arranged in a hole 52 in the cover plate 40. Theplunger 51 is biased upwardly by a spring 53 located beneath a plate 54which extends beyond the diameter of the hole 52. Upon displacement ofthe ring 41, the plate 49 pushes plunger 51 activating the release valve39.

An alternative activating mechanism is shown in FIG. 12. The rotor 4comprises substantially the same arrangement, however the lid 43comprises activating valves 42′ which comprise a piston housing 44′, apiston 46′, a return spring 47′ and a hose 48′ arranged between thepiston housing 44′ and the piston 46′. The hose 48′ links the activatingvalves 42′ and leads to a pneumatic or hydraulic fluid supply (notshown). Upon an increase in pressure in the hose 48′, the piston 46′ isdisplaced, activating the release valve 39 in the same way as thatdescribed above with reference to FIG. 11.

Referring now to FIGS. 3 and 4, there is shown a hydraulic motor 55arranged on the lid 40 of the stator 5. The hydraulic motor 55 ismoveably arranged at one end on a shaft 56 which is fixed to the lid 40of the stator 5. A piston and cylinder 57 is fixed at one end to thestator 5, and at the other end to one side of the hydraulic motor 55. Ahydraulic pump 58 is arranged on the rotor 4.

FIG. 5 shows the hydraulic motor 55 provided with a mounting bracket 59fixed to the static base thereof. The mounting bracket 59 is providedwith a hole through which drive shaft 60 projects. The drive shaft 60has splines on to which a gear 61 is mounted. A disk 63 is mounted on abearing 62 which is mounted on the drive shaft 60 below the gear 61. Thegear 61 and disk 62 are retained on the drive shaft 60 by a c-clip 64.The mounting bracket 59 has two flanges, one provided with a hole forproviding attachment means to the piston and cylinder 57, and the otherprovided with a lug 65 arranged substantially in parallel therewithwhich supports a hose 66 through which the shaft 56 is rotatablyarranged. The end of the shaft 56 is fixed to the lid 40 of the stator5.

FIG. 6 shows the hydraulic pump 58 provided with a mounting bracket 67fixed to the static base thereof. The mounting bracket 67 is providedwith a hole through which a driveable shaft 68 projects. The driveableshaft 68 has splines on to which a gear 69 is mounted. A disk 70 isintegral with and below the gear 69 driveable shaft 68. The gear 69 anddisk 70 are retained on the driveable shaft 68 by a cap 71.

Referring back to FIGS. 3A, and 3B the gear 61 of the hydraulic motor 55is out of engagement with the gear 69 of the hydraulic pump 58. Thepiston and cylinder 57 is retracted.

Referring back to FIG. 4, the gear 61 of the hydraulic motor 55 ismeshing with the gear 69 of the hydraulic pump 58. The piston andcylinder 57 has been operated by pneumatic or hydraulic fluid in to anextended position and has moved the hydraulic motor 55 towards thehydraulic pump 58.

The outer diameter of the disk 63 is of slightly smaller diameter thenthe gear 61, as is the corresponding disk 70 of the hydraulic pump 58.This controls the depth to which the teeth of the gears 61 and 69 canengage. This improves overall efficiency and reliability. It will beappreciated that disks of any diameter may suffice, as long as theymaintain the distance between gears.

Referring now to FIGS. 7 to 10 there is shown a schematic of the parthydraulic, part mechanical circuit of the apparatus of FIG. 1 at variousstages of operation. The circuit is generally identified by referencenumeral 100.

The circuit 100 comprises a hydraulic pump 58 which is driveable byhydraulic motor 55. The circuit 100 also comprises piston and cylinders9, 10 and 11 for engaging a tubular, two accumulators 101 and 102 forstoring a charge for disengaging the cylinders from engagement with atubular, a hydraulic circuit 103 and release valves 38 and 39.

In use, initially the hydraulic circuit 103 is not pressurised. Theopening 8 of the rotor 4 is in line with the opening 8′ of the stator.The hydraulic pump 58 is now situated opposite the opening 8, 8′ at therear of stator 5. The hydraulic motor 55 is in a retracted position(FIG. 3).

When it is desired to use the drill pipe tong, the tong is placed arounda box of a stand of tubulars which is to be connected to a string oftubulars, through opening 8, 8′. The piston and cylinder 57 is actuated,extending the piston from the cylinder which moves the hydraulic motor55 towards the hydraulic pump 58. The gear 61 of the hydraulic motor 55meshes with the gear 69 of the hydraulic pump 58. The hydraulic motor 55is driven by an external hydraulic fluid supply (not shown) on the rigfloor (FIG. 4). The hydraulic motor 55 drives the hydraulic pump 58which pumps hydraulic fluid from a tank 104 (shown schematically as aseparate tank, although is preferably a single tank) through a line 105into a continuation of line 105 in a block 106. The hydraulic fluidflows past check valves 107 an 108. Pressure increases in the cylinders18, 19 and 20 in front of the pistons 15, 16 and 17, which moves thecylinders 18, 19 and 20 into engagement with the box of the tubular tobe gripped. Simultaneously, hydraulic fluid flows past check valve 108into accumulators 101 and 102. Pneumatic pressure in the accumulatorsbuilds up to a predetermined level such as 150 Bar, at which point apreset valve 109 closes and prevents further pressure build up in theaccumulators 101 and 102 (FIG. 8). At this point, hydraulic fluid onlyflows into the cylinders 18, 19 and 20. Hydraulic fluid behind thepistons 15, 16 and 17 is expelled through lines 110, 111 and 112,through flow divider 113, through lines 114, 115 into line 116, intocommon line 117, through line 118 a valve 118 b into the cylinders 18,19 and 20 in front of the pistons 15, 16 and 17. It should be noted thatfluid from behind the piston flows to the front of the piston, therebyonly requiring a small amount of fluid to be drawn from the tank 104. Aflow restrictor 118 inhibits egress of fluid out into tank 104 until thejaws are in firm engagement with the box of the stand of tubulars atwhich point hydraulic fluid leaks through a flow restrictor 118 and intotank 104 via connection 119, thus inhibiting over engaging the jaws 24,25 and 26. A hydraulic lock on the front of the pistons 15, 16 and 17inhibits the jaws 24, 25 and 26 from disengaging during rotation.

The flow divider 113 comprises three rotors 121, 122 and 123 arranged ona common shaft 24. When hydraulic fluid flows across the rotors 121, 122and 123, the rotors allow equal volumes of fluid to pass, therebyensuring even movement of the jaws 24, 25 and 26 arranged on thecylinders 18, 19 and 20.

Flow restrictor 118 allows fluid to flow therethrough slowly. Thisinhibits sudden movement of the cylinders 18, 19 and 20.

When a predetermined setting pressure is reached, an indicator 125moves. This occurs due to valve 126 being set to open at a predeterminedpressure, such as 280 Bar. This allows hydraulic fluid to flow throughline 127 at a pressure above 280 Bar, say at 287 Bar. If the indicator125 needs more than 5 Bar pressure to move, the indicator will now moveinto an extended position, as shown in FIG. 9. Hydraulic fluid at agreater pressure is expelled in to the tank 104.

The hydraulic motor 55 is now swung about shaft 56 by activating pistonand cylinder 57 (FIG. 9). Gears 61 and 69 are now out of engagement. Therotor 4 is now rotated relative to the stator 5 to tighten the screwconnection between tubulars to a predetermined torque. In this state,the cylinders 18, 19 and 20 are held engaged against the tubular byhydraulic fluid being prevented from escaping by check valve 107, andrelease valves 38 and 39 being in a closed position.

Fluid is retained in the accumulators 101 and 102 by check valve 108,and a check valve 126 which is maintained in a closed position byhydraulic fluid at greater pressure and by check valve 127 if thepressure is lower on the opposing side of check valve 126.

A particular advantage of the system described is the fact that anexternal power source can be used to drive the hydraulic motor 55, andthis does not need disconnecting before the motor 4 is rotated becauseit is a simple matter to engage and disengage the motor 55 and the pump58.

Once the rotor 4 stops rotating, the jaws 24, 25 and 26 may bedisengaged form the tubular. This is carried out by pneumatic orhydraulic fluid being pressurised in activating valves 42 whichactivates release valves 38 and 39, as described above with reference toFIGS. 11 and 12. This releases high pressure hydraulic fluid in controlline 128 hence, a reduced pressure occurs on one side of a logic valve129. The logic valve 129 shifts from a closed to an open position whichallows high pressure hydraulic fluid to flow from in front of thepistons 15, 16 and 17 through line 130.

The logic valve 131 also shifts from a closed position to an openposition as high pressure hydraulic fluid in line 132 and a reducedpressure occurs in line 128 on the opposing side of the logic valve 131,allowing high pressure fluid from the accumulators 101 and 102 to flowthrough the logic valve 131, through a restrictor 133. The high pressurehydraulic fluid from the accumulators 101, 102, opens slide valve 134and passes therethrough, into line 117, through flow divider 113 andinto cylinders 18, 19 and 20 behind pistons 15, 16 and 17. The jaws 24,25 and 26 are hence disengaged from the tubular and retracted therefrom.

It should be noted that hydraulic fluid passes out from in front of thepistons 15, 16 and 17 into the line 130, through logic valve 129,through restrictor 135, through slide switch 134, into line 117, throughflow divider 113 into the cylinders 18, 19 and 20 behind the pistons 15,16 and 17. In this way, only an amount of hydraulic fluid equal to thedifference in volumes between the volume in front of the pistons 15, 16and 17 when in the fully extended position and the volume behind thepistons 15, 16 and 17 when in the fully retracted position is requiredto be held in the tank 104. This excess fluid flows through connection119 and into tank 104.

It is also envisaged that the apparatus could be used with thin walledpipe, as it is relatively simple to alter the force applied to the pipeby the jaws. The invention will also be applicable for any tubular orpipe such as casing, tool strings and drill pipes.

It is also envisaged that the accumulator could take the form of aspring or a battery.

It will be appreciated that although the engagement mechanism describedcomprises gears 61, 69 arranged on the motor 55 and pump 58 respectivelyany suitable engagement mechanism can be used. For example, a clutch orfriction drive could be employed to engage and disengage the motor fromthe pump. However, a particular advantage of gears 61, 69 rotating inthe same place as the rotor 4 is that if the motor 55 is not disengagedfrom the pump 58 before the rotor 4 is rotated, the components avoidserious damage.

What is claimed is:
 1. An apparatus for facilitating the connection ofpipes and comprising a rotary and a stator, the rotary comprising atleast one hydraulically actuated jaw, and a pump arranged on the rotaryfor pumping hydraulic fluid for actuation of the at least one jaw, thestator comprising a motor arranged on the stator, so that rotationalenergy can be transferred from the motor to the pump in an operationalconfiguration, characterized in that the motor comprises driving meansand the pump comprises pump driving means, the driving means and pumpdriving means being mechanically engageable.
 2. The apparatus of claim1, wherein the driving means and the pump driving means are rotatable inthe same plane as the rotary.
 3. The apparatus of claim 2, wherein themotor is rotatably arranged on the stator via a shaft so that the motorcan be moved in and out of engagement with the pump by rotating themotor around the shaft.
 4. The apparatus of claim 3, wherein a pistonand cylinder is fixed at one end to the stator, and at the other end tothe motor for moving the motor to bring the driving means and the pumpdriving means in and out of engagement.
 5. The apparatus of claim 1wherein the motor comprises a first gear and the pump comprises a secondgear, the first gear and second gear being engageable to transfer saidrotational energy.
 6. The apparatus of claim 5, wherein the first gearis mounted on a drive shaft and the second gear is mounted on adriveable shaft, and wherein a first disc is mounted on the drive shaftand a second disc is mounted on the driveable shaft so that, when thefirst gear and second gear engage, the first disc contacts the seconddisc so as to control the depth to which the teeth of the first gear andthe second gear mesh with each other.
 7. The apparatus of claim 1,wherein the rotary comprises at least one piston arranged in a cylinderfor actuating said at least one jaw, and a hydraulic circuit linking afirst chamber in front of said piston and a second chamber to a rearside of said piston such that, in use, hydraulic fluid is expelled fromone of said first or second chambers and replenishes the other of saidfirst and second chambers.
 8. The apparatus of claim 7, comprising atleast two pistons, each arranged in a respective cylinder.
 9. Theapparatus of claim 8, further comprising a flow divider.
 10. Theapparatus of claim 7, further comprising a tank for holding hydraulicfluid.
 11. The apparatus of claim 7, further comprising at least oneaccumulator holding a charge for release of the at least one jaw fromengagement with a pipe.
 12. The apparatus of claim 1, wherein the rotarycomprises at least one piston arranged in a cylinder for actuating saidat least one jaw and a hydraulic circuit, wherein said hydraulic circuitcomprises a valve preventing return flow of hydraulic fluid and arestriction such that, in use, the arrangement allows a finite force tobe applied to said pipe.
 13. A method for facilitating the connection ofpipes, comprising mechanically engaging a motor attached to a statorwith a pump attached to a rotor and transferring rotational energy fromthe motor to the pump, enabling the pump to drive hydraulic fluid toactuate at least one jaw.
 14. The method of claim 13, comprising thestep of moving the motor from a first position in which it is disengagedfrom the pump to a second position in which the motor and the pump areengaged to transfer rotational energy from the motor to the pump. 15.The method of claim 13, further comprising expelling hydraulic fluidfrom one of the front or rear sides of at least one piston arranged in acylinder to actuate the at least one jaw for gripping the pipe, andreplenishing the other of said front or rear sides of said piston. 16.The method of claim 13, further comprising driving hydraulic fluidaround a hydraulic circuit to actuate at least one piston arranged in acylinder to actuate the at least one jaw for gripping the pipe, andallowing hydraulic fluid to leak from said hydraulic circuit such thatsaid at least one jaw applies a finite force to said pipe.
 17. A methodfor facilitating the connection of pipes, the method using the apparatusas claimed in claim 12, the method comprising the step of allowinghydraulic fluid to leak from said hydraulic circuit such that said atleast one jaw applies a finite force to said pipe.
 18. A method forfacilitating the connection of pipes, the method using the apparatus ofclaim 7, the method comprising the step of expelling hydraulic fluidfrom one of said front or rear sides of said piston and replenishing theother of said front or rear sides of said piston.
 19. An apparatus forfacilitating the connection of pipes, comprising: a rotary comprising atleast one hydraulically actuated jaw; a stator; a motor arranged on thestator and comprising a driving member, wherein the motor is actutatablebetween a first position and a second position; and a pump arranged onthe rotary for pumping hydraulic fluid for actuation of the at least onejaw and comprising a driving member, wherein the motor driving memberand the pump driving member are engageable, when the motor is in thesecond position, for transferring energy from the motor to the pump.